The present invention relates generally to heating appliances such as toasters or toaster ovens, and more specifically to a shell structure for a heating appliance that includes an open end panel through which components may be inserted during assembly of the heating appliance.
A conventional heating appliance, such as a toaster or toaster oven, generally includes a shell formed from three separate panels. a bottom panel and two end panels. During manufacture of the toaster, these panels, along with a plurality of electrical and mechanical components, are assembled to construct the toaster. FIG. 1 is an isometric view of a conventional toaster 200 with its external case (not shown) removed to illustrate a shell 202. The toaster 200 is described merely as an example of a conventional toaster, and other similar prior art configurations will be understood by those skilled in the art. The shell 202 is formed from a bottom panel 204, a rear end panel 206 and a front end panel 208. Each end panel 206, 208 is attached to the bottom panel 204 through tabs (not shown) that are inserted in respective slots 210, 212 in the bottom panel, as shown for the end panel 208. A first outer heating element 214 and second outer heating element 216 are mounted between the end panels 206, 208, each heating element generating heat to toast food items during operation of the toaster. The heating elements 214, 216 include respective first terminals 217, 219 extending through corresponding apertures in the front end panel 208 and also typically includes a second terminal (not shown) extending through a corresponding aperture (not shown) in the rear end panel 206. Each of the electrical terminals is adapted to receive a respective power signal that is applied to circuitry (not shown) on the heating element 214, 216 to generate heat for toasting food items. To provide added mechanical support for the heating elements 214, 216, a stringer (not shown) is typically attached between the end panels 206, 208 along the top edge of each heating element. A center heating element 218 is positioned between the outer heating elements 214, 216, and generates heat to toast respective food items between the element 218 and the outer heating elements 214, 216. The center heating element 218 also typically includes a terminal 221 extending through an aperture in the front end panel 208 and a terminal (not shown) extending through an aperture (not shown) in the rear end panel 206. None of the electrical terminals 217, 219, 221 contact the front panel 208.
The toaster 200 further includes an outer bread guard 220 positioned inside the end panel 214, and an identical outer bread guard 222 positioned inside the side panel 216. Two inner bread guards 224 and 226 are positioned on both sides of the center heating element 218. Each of the bread guards 220-226 includes a horizontal member 228 and vertical members 230, as shown for the bread guard 220. A first bread cavity 232 is defined between the bread guards 220 and 224, and a second bread cavity 234 is defined between the bread guards 222 and 226. The bread guards 216-222 function to protect bread placed between the bread guards from the heating elements 214-218 during operation of the toaster 200.
A first bread tray (not shown) is contained within the first bread cavity 232 and functions to support a piece of bread as it is lowered into and raised from the bread cavity. A second bread tray (not shown) is similarly positioned within the second bread cavity 234 to support another piece of bread in that bread cavity. Each of the bread trays includes a lever 234 extending through slots 224 and 226, respectively, in the front end panel 208. The levers 234 are pushed down to lower the respective pieces of bread on the bread trays into the bread cavities 232, 234. As the bread trays are pushed down, the outer bread guards 220, 222 move toward the center of the corresponding bread cavity 232, 234, as shown for the bread guard 222. In this way, the bread guards 220-226 position the bread towards the centers of the bread cavities 232 and 234 so that the bread placed on the bread trays is positioned for optimum toasting. The toaster 200 further includes an electronic circuit 236 mounted on the bottom panel 204. Although not shown in FIG. 1, the circuit 236 is typically coupled to the terminals 217-221 and other components of the toaster 200 to control its operation.
During manufacture of the toaster 200, the heating elements 214, 216, and 218, bread guards 220-226, and a plurality of other electrical and mechanical components must be assembled. It is desirable to automate as much of the manufacturing process as possible in order to reduce the cost and increase the reliability of the toaster 200. With the conventional shell 202, however, automating the assembly process is difficult due, in part, to the order in which components must be assembled. For example, as previously described the heating elements 214-218 include respective terminals 217-221 that extend through apertures in the end panels 206, 208. As a result, to position the heating elements 214-218 between the panels 206, 208, one end panel is typically mounted to the bottom panel 204 and then the terminals inserted in the corresponding apertures in that end panel. The terminals at the opposite ends of the elements 214-218 are thereafter inserted in the corresponding apertures in the other end panel 206, 208 and this panel is attached to the bottom panel 204. As will be understood by those skilled in the art, this process is difficult to automate.
In addition to difficulties presented in automating manufacture, the conventional shell 202 is not very sturdy once assembled. This is due primarily to the end panels 206, 208 being fastened to the bottom panel 204 through tabs located at one end. While the end panels 206, 208 could be fastened more securely to the bottom panel 204 to make the shell 202 more sturdy, such as by welding the end panels to the bottom panel, this would increase the cost of manufacturing the toaster 200. Another difficulty presented by the conventional shell 202 is the positioning of the heating elements 214, 216 near the ends of the end panels 206, 208. When the heating elements 214, 216 become hot during operation, a significant amount of heat may be radiated outward away from the cavities 232, 234. This outward radiated heat may heat an external case (not shown) enclosing the shell 202 to an unacceptably high temperature. It is desirable for the external case to have xe2x80x9ccool touchxe2x80x9d sides, meaning that the sides of the case remain cool even during operation. A panel (not shown) may be placed between the heating elements 214, 216 and the external case, but this requires additional labor and parts, which increase the cost of the toaster 200.
There is a need for a shell structure for a heating appliance that is relatively sturdy, enables automated assembly of the toaster, and enables cool-touch sides to be easily constructed.
According to one aspect of the present invention, a shell for a heating appliance includes first and second side panels and front and rear end panels. The front end panel has first and second sub panels and each sub panel has a vertical edge. The vertical edges of the first and second sub panels are spaced apart to form an opening between the vertical edges that allows the insertion of components through the opening during assembly of the heating appliance. Each sub panel includes an aperture extending to the corresponding vertical edge. The aperture is adapted to receive a portion of one of the components that extends beyond an outer surface of the sub panel. Each side panel may include a mounting panel formed at a bottom edge of the side panel, the mounting panel being adapted to receive a portion of one of the components.
According to another aspect of the present invention, a first side heating element is attached on the inside of the first side panel and includes a terminal extending through the aperture in the first sub panel. A second side heating element is attached on the inside of the second side panel and includes a terminal extending through the aperture in the second sub panel. A center heating element is attached to the second end panel between the first and second side heat elements. The center heating element includes a terminal extending through an aperture in the second end panel. Each of the first and second side heating elements and the center heating element operates responsive to a power signal being applied on the corresponding terminal to generate heat.
According to a further aspect of the present invention, a method of manufacturing a toaster includes providing a shell having first and second side panels and first and second end panels. The first end panel has an opening. A first outer heating element is inserted through the opening and attached to the first side panel. A second outer heating element is inserted through the opening and attached to the second side panel. A center heating element is inserted through the opening and attached to the second end panel. Outer bread guards may also be inserted through the opening, each outer bread guard being attached adjacent a corresponding outer heating element.
According to a further aspect of the present invention, a unitary shell structure for a heating appliance includes first/and second side panels, a rear end panel, and first and second front end panels. All of the panels are integrally formed from a single piece of material, such as, for example, metal. Each of the first and second front end panels has a vertical edge, the vertical edges of the first and second front end panels being spaced apart to form an opening between the vertical edges that allows the insertion of components through the opening during assembly of the heating appliance. Each of the first and second front end panels includes an aperture extending to the corresponding vertical edge, the aperture being adapted to receive a portion of one of the components that extends beyond an outer surface of the front end panel.